The principal functions of Core B, the Clinical Core of the Alzheimer's Disease Research Center (ADRC), are: to recruit, characterize, and follow subjects as part of our clinical and neurobiological investigations of the behavior-brain abnormalities that occur in aging and in Alzheimer's disease (AD); and to provide a resource for all investigations at the Johns Hopkins Medical Institutions (JHMI) involved in the study of aging and AD, including clinical trials, genetic studies, tissue repositories, and imaging protocols. Because cognitive performance in the elderly varies widely, ranging from normal cognition to severe dementia, the staff of this Core has assembled several cohorts (about 700 subjects) to examine the full spectrum of cognitive states associated with old age. Extending our previous studies of the clinical course of well-established cases of AD, this Core will now emphasize investigations of nondemented elderly subjects and patients in the early stages of AD. Thus, this Core will follow: 97 severely demented members of the original ADRC cohort (Cohort 1) and their 40 controls; about 400 subjects of the Baltimore Longitudinal Study of Aging (BLSA); and 100 new subjects with early AD and 50 additional controls (Cohort 2), with particular attention to the recruitment of African-American subjects. Studies of Cohort 1 focus on clinical and nursing care issues, the education of families of patients in the late stages of AD, and clinical-pathological investigations of this longitudinally followed cohort with a diagnosis of probable AD. Cohort 2 will be used for our neuropsychological, neuroimaging, and noncognitive investigations of the early stages of AD, whereas the BLSA cohort will serve as the focus for our clinical, imaging, and pathological studies dealing with normal aging and early stages of dementia. The Data Center, staffed by professionals with expertise in statistical methods for longitudinal studies and analytical approaches to data management, functions to collect, maintain, and analyze the demographic and clinical information on all subjects. The staff, with expertise in neurology, psychiatry, neuropsychology, statistics, and nursing, interacts closely with investigators in the neuropathology Core and supports research in Kawas' Project and Pilot Projects. Complementing the investigations of experimental models in Projects 18-20 and Wilcox's Pilot, this Core is a central clinical resource for all investigations of human subjects in the ADRC.